.out{
  background-color: aqua;
  width: 500rpx;
  height: 500rpx;
  .box{
    width: 350rpx;
    height: 350rpx;
    background-color: brown;
    .inner{
      width: 200rpx;
      height: 200rpx;
      background-color: orchid;
    }
  }
}